Low inherent viscosity-high glass transition temperature enhancing agents produced by suspension polymerization as an overpolymer on polyvinyl chloride resins

ABSTRACT

Various fabrication properties of polyvinyl chloride are improved such as melt flow by treating the polyvinyl chloride resin with a low inherent viscosity-high glass transition temperature enhancing agent. The treatment occurs as a suspension overpolymerization on the polyvinyl chloride resin by reacting at least one high glass transition temperature enhancing agent with at least one substantially water insoluble chain transfer agent. The formed high glass transition temperature-low inherent viscosity agent imparts a high glass transition temperature to the polyvinyl chloride resin and also reduces the inherent viscosity to a level below the inherent viscosity formed by the combined effect of the polyvinyl chloride resin and the glass transition temperature agent.

FIELD OF THE INVENTION

The present invention relates to a suspension overpolymerization of high glass transition temperature-inherent viscosity enhancing agents on polyvinyl chloride resin with the treated resin being particularly suitable for various melt type fabrication processes and applications.

BACKGROUND

Heretofore, certain types of polymers or copolymers were blended with polyvinyl chloride (PVC) resins to increase the glass transition temperature thereof. Such blends containing the glass transition temperature improving polymers or copolymers generally were unsatisfactory for various melt type fabrication processes such as custom injecting molding (CIM) applications. When glass transition temperature improving polymers or copolymers having a low inherent viscosity in and of themselves were blended with PVC resins, the powder flux in various processing devices such as an extruder, a Bandbury, a mill, or an injection molding machine, was often unsatisfactory. Hence, glass transition temperature polymers or copolymers were utilized having high inherent viscosities. Such high inherent viscosities decreased the melt flow when blended with PVC and limited the usefulness thereof in melt type fabrication processes.

SUMMARY OF THE INVENTION

It is therefore an aspect of the present invention to provide a terated PVC resin suitable for melt type processes and fabrication applications. It is also an aspect to provide a low inherent viscosity-high glass transition temperature agent treated PVC resin which is easily processed, has excellent melt flow properties with regard to melt type processes, and has excellent dispersion of the glass transition treating agent therein. The PVC resin can be any type of resin as made by mass, emulsion, suspension, or dispersion polymerization with mass and suspension resins being preferred. The treated PVC resin is made by a suspension process whereby a mixture of the chain transfer agent, the high glass transition temperature agent forming monomers and initiators are applied to the PVC resin and are usually absorbed thereon. The PVC resin with the applied mixture thereon is suspended in water and the overpolymerization of the high glass transition temperature agent forming monomers occurs on the PVC resin at suitable temperatures. Some grafting of the monomers to the PVC resin occurs. The chain transfer agents are substantially water insoluble compounds such as various alkyl mercaptans, the various alkenes or benzoalkenes containing at least one allylic hydrogen atom, the various chlorinated or bromonated alkanes, alkenes, or alkynes and the various high molecular weight aldehydes. The amount of water utilized in the suspension overpolymerization of the high glass transition temperature enhancing agent and the chain transfer agent is usually small to make efficient use of a reaction vessel.

The invention will be better understood by reference to the following detailed description.

DETAILED DESCRIPTION

In accordance with the present invention, generally any polyvinyl chloride particulate resin can be utilized such as resin made by suspension polymerization, dispersion polymerization, emulsion polymerization, mass polymerization, and other types of polymerization as well known to the art and to the literature. Various copolymers of polyvinyl chloride resin can also be utilized although such is not preferred in the present invention. Such comonomers are well known to the art and to the literature with a few representative examples including the various halides, the various vinylidene halides, vinyl acetate, esters of acrylic acid, esters of methacrylic acid, various alkenes, and the like. It is also to be understood that by the term polyvinyl chloride is included chlorinated polyvinyl chloride resins containing a total of from about 57% to about 72% by weight of chlorine therein.

The polyvinyl chloride particulate resins of the present invention are treated with the high glass transition temperature-inherent viscosity enhancing treating agent before the application thereto of any compounding aids, processing aids, conventional additives, and the like. As noted above, the high glass transition temperature-inherent viscosity enhancing treating agent is made by the suspension polymerization of a high glass transition temperature agent forming monomers and a low inherent viscosity enhancing agent on the polyvinyl chloride particles, that is as a suspension overpolymerization.

Generally, any conventional or polyvinyl chloride glass transition temperature enhancing agent as well as those known to the art and to the literature can be utilized to increase the glass transition temperature of the polyvinyl chloride resin. Such agents are generally polymers or copolymers containing conventional amounts of the various components and are made from one or more styrene type monomers such as styrene, alpha-methylstyrene, para-methylstyrene, vinyl nitriles such as acrylonitrile and methacrylonitrile, the various esters of methacrylic acid such as methylmethacrylate, the various maleimides, the various indenes, the various norbornenes including norbornadiene, the various unsaturated acid anhydrides such as maleic anhydride, including derivatives thereof, as well as combinations of the above. Preferred glass transition temperature enhancing agents of the present invention include styrene, acrylonitrile, alpha-methylstyrene, with a copolymer of alpha-methylstyrene and acrylonitrile being highly preferred.

The high glass transition temperature enhancing agent forming monomers are generally utilized as a basis with regard to the other components of the present invention. Accordingly, the amount of polyvinyl chloride particulate resin utilized is generally from about 50 to about 2,000 parts by weight for every 100 parts by weight of the glass transition temperature forming monomers. A more desired amount of the polyvinyl chloride particulate resin is from about 75 parts to about 500 parts by weight, preferably from about 100 to about 350 parts by weight with from about 125 to about 300 parts by weight being highly preferred based upon 100 parts by weight of the high glass transition forming monomers. On a percentge basis based upon the amount of overpolymerization, that is the amount of the high glass transition temperature agent forming monomers, the chain transfer agent and the polyvinyl chloride particulate resin, the amount of the high glass transition temperature forming agents is from about 5% to about 70%, and preferably from about 25% to about 45% by weight. Naturally, the high glass transition temperature enhancing agents impart or increase the glass transition temperature of the various polyvinyl chloride particulate resins utilized. Such increase in the glass transition temperature of the resulting overpolymerized polyvinyl chloride particulate resin is generally at least 5° C., desirably at least 12° C., and preferably at least 20° C.

The overpolymerization reaction of the high glass transition temperature agent forming monomers with the chain transfer agents occurs as a suspension reaction, that is in the presence of water and the polyvinyl chloride particulate resin. Inasmuch as polyvinyl chloride is an organic compound, it forms a separate phase in the water. Since the suspension polymerization occurs essentially and primary through agitation, that is no emulsifiers, surfactants, suspending agents, and the like are utilized, the high glass transition temperature agent forming monomers as well as the chain transfer agents will migrate to the polyvinyl chloride particles and react thereon, and hence, the overpolymerization reaction. The amount of water utilized in the suspension overpolymerization reaction can vary over a very wide range. For example, up to near infinite amounts of water can be utilized. However, to make efficient use of the reaction vessel, small amounts of water are desirably utilized. The amount of water utilized is generally based upon the solids content of the solution and hence of the polyvinyl particulate resin, as well as the high glass transition temperature monomer. Desirably, the amount of water is such that the total solids content, i.e. the amount of polyvinyl chloride particulate resin, is generally 5% or greater, desirably from about 10% to about 60%, and preferably from about 25% to about 50% by weight based upon the total weight of the solids and the water at the end of the polymerization.

In order for the chain transfer agents to be effective, they are generally water insoluble inasmuch as water soluble agents will dissolve within the water and, hence, not effect overpolymerization on the polyvinyl chloride particulate resin. The chain transfer agents must also be capable of reacting with the high glass transition temperature agent forming monomers and to impart low viscosities, that is reduce the inherent viscosity of the glass transition temperature enhancing agents by apparently shortening the chain length thereof and hence reduce the average inherent viscosity of the overpolymerized polyvinyl chloride particulate resin. When the preferred types of polyvinyl chloride resins such as mass and suspension resins are utilized, the resins are generally porous and have voids, cracks, fissures, etc., therein. Hence, the reaction with regard to these types of resins is not solely a surface phenomenon since the reactants actually penetrate, permeate, or are absorbed into the porous polyvinyl chloride polymer and thus the reaction also occurs therein. Naturally, the overpolymerization is carried out in the presence of an inert atmosphere such as nitrogen, or the like.

The chain transfer agents of the present invention can generally be any substantially water insoluble organic compound which contains an active hydrogen or an active halogen. By the term "substantially water insoluble", it is meant that the solubility of the chain transfer agent is generally less than 20 grams and desirably less than 10 grams per 100 grams by weight of water. A suitable class of a water insoluble chain transfer agent are the various alkyl mercaptans having from 5 to 22 carbon atoms which are generally water insoluble. Generally, the higher molecular weight alkyl mercaptans are preferred such as those having 8 to about 18 carbon atoms. Examples of specific alkyl mercaptans include t-decyl mercaptan, t-dodecyl mercaptan, t-octyl mercaptan, and the like. Another type of chain transfer agent are the various alkenes or benzoalkenes (i.e. aromatic alkenes) which contain at least one allylic hydrogen atom and has a total of from about 3 to 20 carbon atoms, and preferably from 3 to 12 carbon atoms, such as propene, 1-butene, 2-butene, indene, and the like. The various chlorinated or brominated alkanes, alkenes or alkynes having 1 to 12 carbon atoms can also be utilized with specific examples including chloroform, bromoform, trichloroethylene, allylchloride, and the like. Another class of suitable chain transfer agents are the aldehydes which are water insoluble. Generally, these are only the compounds which have at least 6 carbon atoms or at least 8 carbon atoms to about 15 carbon atoms such as hexanal. The alkyl mercaptans are preferred with t-dodecyl mercaptan, t-octyl mercaptan, and t-decyl mercaptan being highly preferred.

As noted above, the overpolymerization of the various high glass transition temperature enhancing agent forming monomers on the polyvinyl chloride particles increases the inherent viscosity of the polyvinyl chloride resin. Accordingly, an amount of chain transfer agent is utilized so that upon reaction with the high glass transition temperature agent, the inherent viscosity of the overall composition, that is the overpolymerized polyvinyl chloride particulate resin is reduced. Desirably, the inherent viscosity is reduced to at least the original inherent viscosity of the polyvinyl chloride particles, that is to the inherent viscosity level of the polyvinyl chloride resin before any overpolymerization reaction thereon. More desirably, the reduction is to at least 5% and preferably at 15% below the inherent viscosity of the original polyvinyl chloride resin, that is before any overpolymerization reaction thereon. When the compositions of the present invention are utilized with regard to custom injection molding applications or processes, inherent viscosity of the overpolymerized polyvinyl chloride particulate resin is generally from about 0.25 to about 0.7, and preferably from about 0.4 to about 0.6. For extrusion applications, the inherent viscosity can be about 0.7 to about 1.2 and preferably from about 0.5 to about 1.2. The inherent viscosity is measured in accordance with ASTM 358C which briefly involves utilizing 0.2 grams of the treated polyvinyl chloride resin dissolved in same 50 ml of cyclohexanone solvent at 25° C. In order to achieve the above-noted inherent viscosity values, the effective amount of the chain transfer agent is generally from about 0.3 to about 20 millequivalents per 100 parts by weight of the glass transition temperature agent forming monomers, desirably from about 1.0 to about 15 millequivalents, and preferably from about 2 to about 10 milliequivalents.

The reaction of the high glass transition temperature agent forming monomers with an effective amount of the water insoluble chain transfer agent and an oil soluble free radical initiator is carried out in an oxygen-free environment as in an enclosed vessel having a suitable mixing means to provide sufficient agitation to conduct the suspension polymerization. That is, inasmuch as surfactants, emulsifiers, etc., are not utilized, a true suspension reaction is conducted. Examples of such suitable mixing reaction vessels include a ribbon blender, rotating autoclaves, or a conventional polymerization vessel with sufficient agitation to keep the polyvinyl chloride resin and applied monomers, etc., freely suspended. The method of preparation comprises adding polyvinyl chloride to the reactor and purging air therefrom through the use of a vacuum and an inert gas, for example nitrogen, carbon dioxide, and the like. Once the vessel has been purged, suitable and effective amounts of the high glass transition temperature agent forming monomers, water and the chain transfer agents and an oil soluble free radical catalyst are added thereto. Catalysts such as free radical catalysts are generally utilized. The chain transfer agents, the glass transition temperature agent forming monomers, water, and the polyvinyl chloride resin are mixed in the reaction vessel with the glass transition temperature agent monomers being polymerized at suitable temperatures and times. Inasmuch as the monomer is organic and since its system does not include emulsifiers, surfactants, etc., the monomer migrates to the organic polyvinyl chloride resin phase where it coats as well as penetrates any porous resin. Overpolymerization is thus achieved. That is polymerization of the high glass transition temperature agent forming monomers occurs in situ on and in the polyvinyl chloride resin.

The catalysts are desirably oil soluble and water insoluble with high water insolubility being preferred. Two specific groups or classes of free radical initiators are the various azo type initiators as well as the various peroxide type initiators. Examples of specific azo type initiators include 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(isobutyronitrile), and the like. Numerous peroxide initiators are known to the art and to the literature and various types thereof can be utilized such as diacyl peroxides, ketone peroxides, peroxydicarbonates, peroxyesters, dialkyl peroxides, hydroperoxides, peroxyketals, and the like. Examples of specific peroxides include decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, alpha-cumylperoxy pivalate, t-butylperoxy neodecanoate, t-butylperoxy pivalate, t-butylperoxyisobutylate, t-butylperoxy acetate, t-butylperoxy benzoate, dicumyl peroxide, di-t-butyl peroxide, t-butylhyroperoxide, 2,2-di-(t-butylperoxy)butane, and the like. The amount of the initiators is generally small as from about 0.05 parts to about 1.0 parts by weight and desirably from about 0.10 to about 0.75 parts by weight for every 100 parts by weight of the glass transition temperature agent forming monomers.

The time of the reaction as well as the temperature can naturally vary depending upon the amount of initiator utilized as well as the type of initiator. As a rule of thumb, polymerization of the high glass transition temperature agent forming monomers in the presence of chain transfer agents generally occurs at about 40° C. to about 90° C. with a temperature range of about 50° C. to about 85° C. being preferred. The overpolymerized PVC resin is readily separated from the suspension solution as through filtering, centrifuging, etc.

The low inherent viscosity-high glass transition temperature treated polyvinyl chloride resins of the present invention have several advantages including a low cost to produce because of low raw material and manufacturing costs. Excellent dispersion of the high glass transition temperature agent forming monomers is also obtained. According to the present invention, the ability to utilize the existing suspension polyvinyl chloride plant equipment, the ability to utilize polymerized polyvinyl chloride which has been only partially stripped, excellent melt flow characteristics for utilization in processing equipment such as injection molding equipment, and the like.

The treated polyvinyl chloride resins of the present invention can thus be utilized in various melt type fabrication processes such as extrusion, compression molding, blow molding, injection molding, and the like. The present invention is particularly suitable for custom injection molding. Examples of articles which thus can be produced utilizing the overpolymerized resin of the present invention include bottle, TV housings, pipe fittings, battery jars, applicance housings, and the like. The invention will better understood by reference to the following examples.

EXAMPLE I

General charging procedure, polymerization conditions and work up procedure used for all bottle polymerizations except where noted.

Charging Procedure:

Quart pop bottles were charged by carefully weighing the dry powder PVC, adding the boiled distilled water (carefully weighed), and then adding the solution containing the monomers, initiators, and chain transfer agent, if used (also carefully weighed). The charging was carried out under a nitrogen atmosphere taking special care to eliminate oxygen. The bottles were sealed with a rubber lined cap and pressured with 10 psi nitrogen.

Polymerization Conditions:

The charged, sealed bottles were placed in a 60° C. (unless noted otherwise) constant temperature water bath and tumbled for 16 hours. The bottles were then removed from the water bath, cooled and degassed before removing the cap.

Work-up:

The contents of the bottles were poured on individual suction filters to remove water. Resuspended in isopropanol, refiltered and then dried at 60° C. under vacuum to a negligable heat loss (this usually required about 24 hours drying time). The dried resins were weighed, the heat loss measured and the yield of polymer corrected for the volatile heat loss. The corrected yield was then used to calculate the percentage monomer conversion using the following formulation:

    __________________________________________________________________________     % Monomer Conversion =                                                          ##STR1##                                                                      Effects of the level of monomers charged on the                                properties of a methyl methacrylate/a-methyl styrene                           copolymer overpolymerized on PVC. All quantities are in                        grams. Weight ratio MMA/alpha-methyl styrene = 90/100.                                              1   2   3   4   5                                         __________________________________________________________________________     INGREDIENTS                                                                    PVC (0.54 I.V.)      100 100 100 100 100                                       Boiled Distilled Water                                                                              400 400 400 400 400                                       t-butyl peroxypivalate                                                                              0.3 0.3 0.3 0.3 0.3                                       Methyl Methacrylate  9.9 22.5                                                                               38.7                                                                               60.3                                                                               90                                        Alpha-methyl Styrene 1.1 2.5 4.3 6.7 10                                        PROPERTY OF OVERPOLYMER                                                        Weight % Monomers based on PVC                                                                      10  20  30  40  50                                        % Monomers Conversion                                                                               14.3                                                                               89.1                                                                               95.1                                                                               97.0                                                                               97.9                                      % by wt. non-PVC polymer (actual)                                                                   1.6 18.4                                                                               29.0                                                                               39.4                                                                               49.6                                      Glass transition Tg °C.*                                                                     82.5                                                                               89.3                                                                               94.5                                                                               97.5                                                                               99.2                                      COMPOUNDED PROPERTIES                                                          Glass Transition Temp. Tg °C.                                                                81.2                                                                               81.0                                                                               94.6                                                                               97.3                                                                               99                                        HDT C (D-684 @ 264 psi).sup.(2)                                                                     67.5                                                                               73.0                                                                               77  79.5                                                                               80                                        Izod Impact          2.7 2.0 1.4 1.2 1.1                                       (ft. lbs/inch notch)                                                           density (grams/cc)   1.33219                                                                            1.30113                                                                            1.28146                                                                            1.26465                                                                            1.2478                                    RHEOLOGY.sup.(3) NPOISE X10                                                    190° C. @ 100 sec                                                                            1.62                                                                               2.25                                                                               3.22                                                                               4.25                                                                               4.71                                      190° C. @ 500 Sec                                                                            0.65                                                                               0.83                                                                               1.25                                                                               1.49                                                                               1.53                                      190° C. @ 1000 sec                                                                           0.43                                                                               0.56                                                                               0.75                                                                               0.88                                                                               0.89                                                            PARTS PER 100                                                                  PARTS OVERPOLYMER                                        __________________________________________________________________________     K 120N (Rohm & Haas), 3                                                        an acrylic processing aid                                                      Blendex 310 (Borg Warner),                                                                           15                                                       a methacrylate-styrene-butadiene toughener                                     Advastab TM181,       2                                                        a tin staqbilizer                                                              Mineral Oil           2                                                        Calcium Stearate      2                                                        Calcium Carbonate     2                                                        __________________________________________________________________________      .sup.(2) The HDT test was carried out on unannealed bars 1/8" thick.           .sup.(3) Rheology measured on a SieglaftMcKelvey Rheometer 0.048708 cm di      radius.                                                                        *DuPont Model 1090B differential scanning calorimeter  Tg °C. of        the PVC by itself is 83.1° C.                                     

The ingredients were carefully weighed, dry blended in a Warring blender for one minute and then milled for three minutes after the stock bands on the mill. The milling was carried out on a 6 inch electrically heated laboratory mill with the front roll of the mill at 300° F. and the rear roll at 280° F. The test samples were compression molded 5 minutes at 390° F.

EXAMPLE II

Non-PVC Polymer=80/10/10 wt. % MMA/alpha-methyl styrene/acrylonitrile

Effects of varying the molecular weight of the overpolymer on melt viscosity and heat distortion temp. Samples polymerized 16 hours at 65° C. Everything else is the same as in Example I.

    ______________________________________                                         INGREDIENTS 1       2      3     4    5     6                                  ______________________________________                                         PVC (0.54 IV)                                                                              100     100    100   100  100   100                                Boilded Dist. Water                                                                        400     400    400   400  400   400                                Monomer  --                                                                    A           50      --     --    --   --    --                                 B           --      50     --    --   --    --                                 C           --      --     50    --   --    --                                 D           --      --     --    50   --    --                                 E           --      --     --    --   50    --                                 F           --      --     --    --   --    50                                 ______________________________________                                                  MAKE-UP                                                               MONOMER  phr       A      B    C    D    E    F                                ______________________________________                                         MMA      80        160    160  160  160  160  160                              alpha-methyl                                                                            10        20     20   20   20   20   20                               styrene                                                                        acrylonitrile                                                                           10        20     20   20   20   20   20                               *sulfole 120                                                                            0.8-2.5   1.60   2.0  2.4  3.0  4.0  5.0                              variable                                                                       t-butyl  0.3**     0.800  0.800                                                                               0.800                                                                               0.800                                                                               0.800                                                                               0.800                            peroxypivalate                                                                 ______________________________________                                          *t-dodecylmercaptan chain transfer agent 0.800 g of 75% -- in mineral oil     RESIN                                                                          PROPERTIES 100% PVC                                                                           1      2      3    4    5    6                                  ______________________________________                                         % Monomer Conv.                                                                            --     94.7   94.4 94.6 94.5 93.1 94.9                             I.V. (inherent                                                                             0.54   0.526  0.525                                                                               0.483                                                                               0.466                                                                               0.444                                                                               0.419                            viscosity cyclo-                                                               hexane                                                                         @ 25° C.)                                                               wt. % Non-PVC      32.5   32.3 32.3 32.3 31.9 32.2                             polymer                                                                        ______________________________________                                         1.  COMPOUNDED                                                                     PROPERTIES 100%                                                                PVC.sup.1      1      2    3    4    5    6                                ______________________________________                                         2.  Heat       75.5    81.0 85.0 85.0 84.0 83.0 82.0                               Deflection.sup.2                                                               Temp. °C.                                                           RHEOLOGY                                                                       N(poise × 10.sup.-4)                                                     200° C. @ 100 sec.                                                                 1.02    1.36   1.35 1.28 1.13 1.04 0.94                             200° C. @ 1000 sec                                                                 0.32    0.36   0.34 0.33 0.33 0.31 0.28                             Izod       7.37    1.58   2.53 2.52 2.30 1.69 1.58                             (ft.lbs/inch notch)                                                            ______________________________________                                          1. Recipe and mixing conditions same as Example I.                             2. Heat deflection bars 1/2" × 1/8" × 6" Annealed 24 hours @       80° C. ASTM D684 264 psi.                                         

Conclusion:

The heat deflection temperature remains nearly constant or actually increases while melt viscosity is significantly decreased. This result was truly unexpected. Thus, the heat deflection temperature can be raised while greatly improving processibility leading to either faster extrusion rates in making extruded goods or being able to fill more intricate molds in injection molding.

As apparent from the above data, the inherent viscosities of polyvinyl chloride is reduced. Hence, higher molecular weight polyvinyl chloride resins can be utilized with regard to various melt processing operations wherein a reduced inherent viscosity is desired. Moreover, it can be seen from the above that the heat deflection values generally did not vary with the molecular weight of the overpolymer. This result was truly unexpected in that a decrease in molecular weight usually results in a decrease in heat deflection temperature. This is verified by the below example wherein it is shown that decreasing the molecular weight or I.V. of the backbone PVC to lower the melt viscosity and to improve the processibility (no chain transfer agent) results in the expected lowering of the heat deflection temperature.

    ______________________________________                                         Experimental PVC A IV = 0.540                                                  Experimental PVC B IV = 0.465                                                                  Exp. PVC A                                                                              Exp. PVC B                                            ______________________________________                                         Heat Deflection Temp °C.                                                                  75.5       64.5                                              Izod Impact       7.4        2.3                                               Ft.Lbs/Inch Notch)                                                             Melt Viscosity (N poise × 10)                                            200° C. @ 100 sec                                                                         1.02       0.60                                              200° C. @ 1000 sec                                                                        0.32       0.23                                              ______________________________________                                           PG,19

As apparent from the above Table, lowering the PVC backbone molecular weight to lower melt flow viscosity results in a large drop in heat deflection temperature when no chain transfer agent was utilized.

While in accordance with the Patent Statutes, a best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto, but rather by the scope of the attached claims. 

What is claimed is:
 1. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin, comprising:a polyvinyl chloride resin and a polyvinyl chloride high glass transition temperature-inherent viscosity enhancing agent, said high glass transition temperature-inherent viscosity enhancing agent applied in a suspension to said polyvinyl chloride resin, said polyvinyl chloride high glass transition temperature-inherent viscosity agent made by suspension polymerizing one or more high glass transition temperature agent forming monomers in the presence of an effective amount of a substantially water insoluble chain transfer agent so that the inherent viscosity of said treated polyvinyl chloride resin is reduced, the amount of said chain transfer agent being from about 0.3 milliequivalents to about 20 millequivalents for every 100 parts by weight of said glass transition temperature agent forming monomers, wherein said high glass transition temperature agent forming monomer is a styrene-type monomer, a vinyl nitrile, a maleimide, an indene, a norbornene, an unsaturated acid anhydride, or combinations thereof, the amount of said polyvinyl chloride resin being from about 50 parts to about 2,000 parts by weight for every 100 parts by weight of said one or more monomers.
 2. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 1, wherein said suspension polymerization of said high glass transition temperature agent forming monomers is an overpolymerization on said polyvinyl chloride resin.
 3. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 2, wherein said treated polyvinyl chloride resin has an inherent viscosity reduction to a level of at least the initial inherent viscosity of said polyvinyl chloride resin.
 4. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 3, wherein said chain transfer agent is an alkyl mercaptan having from 5 to 22 carbon atoms, an alkene or an aromatic alkene having at least one allylic hydrogen atom and containing from 3 to about 20 carbon atoms, a chlorinated or brominated alkane, alkene or alkyne having from 1 to 12 carbon atoms, an aldehyde having from 6 to about 15 carbon atoms, or combinations thereof, wherein the amount of said chain transfer agent is from about 1 to about 15 millequivalents for every 100 parts by weight of said glass transition temperature agent forming monomers.
 5. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 4, wherein said chain transfer agent is said alkyl mercaptan having from 8 to 18 carbon atoms, or said alkene or said aromatic alkene having at least one allylic hydrogen atom, and wherein said glass transition agent forming monomer is styrene, alpha-methylstyrene, acrylonitrile, or combinations thereof.
 6. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 5, wherein the amount of said polyvinyl chloride resin is from about 75 parts to about 500 parts by weight for every 100 parts by weight of said one or more monomers, wherein the amount of said water in said suspension polymerization is such that the amount of said PVC solids in said is from about 5% to about 60% by weight based upon the total weight of said solids and said water, and wherein said chain transfer agent is t-dodecyl mercaptan, t-decyl mercaptan, t-octyl mercaptan, or combinations thereof.
 7. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 6, wherein the amount of said chain transfer agent is from 2 to about 10 millequivalents for every 100 parts by weight of said glass transition temperature agent forming monomers, wherein the amount of said polyvinyl chloride solids in said water is from about 25% to about 50% by weight, and wherein said substantially water insoluble chain transfer agent has a solubility of 20 grams or less in 100 grams of water.
 8. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 2, wherein said treated polyvinyl chloride resin has an inherent viscosity reduction to at least 5% below the initial inherent viscosity of said polyvinyl chloride resin, and wherein the glass transition temperature of said polyvinyl chloride resin is increased by at least 5° C.
 9. A low inherent viscosity-high glass transition temperature agent treated polyvinyl chloride resin according to claim 6, wherein said treated polyvinyl chloride resin has an inherent viscosity reduction of at least 15% below the initial inherent viscosity of said polyvinyl chloride resin, and wherein said suspension is created by agitation.
 10. A polyvinyl chloride resin suitable for custom injection molding application comprising the resin of claim
 5. 